Boundary layer concentrations and landscape scale emissions of volatile organic compounds in early spring

Boundary layer concentrations of several volatile organic compounds (VOC) were measured during two cam- paigns in springs of 2003 and 2006. The measurements were conducted over boreal landscapes near SMEAR II measure- ment station in Hyyti¨¨ a, Southern Finland. In 2003 the measuremens were performed using a light aircraft and in 2006 using a hot air balloon. Isoprene concentrations were low, usually below detection limit. This can be explained by low biogenic production due to cold weather, phenolog- ical stage of the isoprene emitting plants, and snow cover. Monoterpenes were observed frequently. The average to- tal monoterpene concentration in the boundary layer was 33 pptv. Many anthropogenic compounds such as benzene, xylene and toluene, were observed in high amounts. Ecosys- tem scale surface emissions were estimated using a simple mixed box budget methodology. Total monoterpene emis- sions varied up to 80µg m 2 h 1 , -pinene contributing typ- ically more than two thirds of that. These emissions were somewhat higher that those calculated using emission algo- rithm. The highest emissions of anthropogenic compounds were those of p/m xylene.